The Deep Dungeon, also known as Midlight's Deep, is an optional, multi-level dungeon accessible in Chapter 4. It is one of the most challenging areas in the game, featuring powerful enemies and unique treasures. To access it, you must visit Warjilis Trade City after certain story events in Chapter 4.
Each level of the Deep Dungeon has specific entry requirements (e.g., a unit with 'Move-Find Item' or 'Teleport'). The enemies here are extremely tough, often featuring high-level monsters and human units with powerful abilities. However, the rewards are well worth the effort, including some of the best equipment in the game. Be prepared for a grueling series of battles.